This paper proposes a new method measuring LED junction temperature based on spectral integral width method,and conducts theoretical analysis and experiment research.This method is mainly divided into three processes:spectral data acquisition,calibration function measurement and junction temperature measurement. First,in order to reduce the measurement cost and improve the accuracy,LED spectral data are collected under normal working current,and a calibration function with a linearity of more than 0.99 can be obtained by using the spectral integration width at different temperatures and the value of a selected reference state,and the junction temperature under any state can be measured in real time through this calibration function.Second,in order to compare the accuracy of this method for measuring junction temperature,this method and the industry mainstream forward voltage method are used for monochrome and white LED respectively.The measurement results of the self-designed junction temperature measurement system based on integral width method and the T3Ster instrument of Mentor Graphics Company in the United States are compared.The maximum deviation of junction temperature measured by the two methods is 2.1 ℃,which is within the acceptable error range.The experimental results show that the integral width method has the characteristics of high efficiency,convenience and low cost,and has a certain application prospect.